1. Field of Invention
This invention relates to a new, practical belt-type apparatus containing therein lead wires for measuring the electrical activity of the heart of a patient when used with an electrocardiograph machine. It is attached to a patient and is useful for taking electrocardiograms instead of the conventional individual wires attached to the patient, one at a time, in order to take an electrocardiogram.
An electrocardiogram, generally referred to as an ECG or an EKG, is a visual display of the electrical activity of the heart. Electrocardiograms are accepted in the field of medicine, particularly cardiology, to be of great value in the diagnosis and management of patients with heart disease, undergoing surgery, in distress for other medical reasons and undergoing routine physical examinations to establish a baseline record of the heart's electrical activity. In cases where a permanent record is desired, the EKG is usually recorded by an electrocardiograph machine on paper made specially for that purpose.
The most commonly performed electrocardiogram is called a "twelve-lead EKG" although it is made with only 10 separate lead wires attached to electrodes that are attached to the body of the patient. Six of the electrodes are attached to the patient's chest at certain known recording zones over the heart. They and their attached lead wires are referred to as the "precordial" electrodes and leads, respectively. Four other wires and their attached electrodes are commonly referred to as the "limb" leads and electrodes, respectively. Each limb of the patient has one limb lead and its electrode attached thereto over commonly accepted recording zones. Such electrodes must be applied one at a time and in the particular case of the precordial electrodes must be placed in the proper sequence over the proper recording area for each lead. In addition, the two arm leads must not be reversed in order to avoid obtaining a faulty EKG tracing (this is not critical for the leg leads). Because of the great number of separate leads and their length, problems with conventional devices often arise, e.g., the wire leads frequently get entangled during normal usage resulting in time delays to perform the next EKG and wires are mistakenly placed over the wrong recording area of the body leading to inaccurate readings that require repeating the test or else untoward errors in patient care and management may result. These events may not only place the patient in potential harm, but also waste the time of the patient, performing technician, and attending physician, thus adding to the cost of medical care.
Conventional precordial EKG electrodes are applied to the body with either suction cups or self-adhesive disposable electrodes. Both devices are prone to falling off, for example, when the patient has large pectoral muscles, is large breasted and/or their chest is hairy, sweaty, and/or the test is performed with the patient partly or completely sitting up. Such circumstances generally lead to additional delay in performing the test. In addition, the reusable suction cups may become unsightly or unsanitary through use particularly when employed in a high volume patient setting such as an emergency room.
2. Prior Art
The prior art reveals several alternative devices for recording EKGs. Mills et al. U.S. Pat. Nos. 4,121,575 and 4,202,433 teach embedding the precordial electrodes in an elastic strip held down by weights at both ends. However, the entire device is not contoured to accommodate patients with large pectoral muscles or breasts nor can it accommodate those who cannot lie completely flat during the test. The greatest interpersonal variability in the distances between patients' precordial recording zones occurs laterally because of the downward curvature of the chest approaching the left flank. Mills et al. fail to take this variabiity into account by fixing the positions of V4, V5 and V6 thus limiting the variety of chest sizes with which it may be used. In addition, weights applied at both ends will tend to lift the centermost electrodes off the chest leading to incomplete recordings from one or more of the central precordial electrodes. Further, neither of the Mills et al. patents describe recording signals from any of the limb leads.
Arkans, U.S. Pat. No. 4,328,814, describes a precordial strip of six electrodes that are self-adhesive and adjustable to accommodate a wide variety of body habitus'. In addition, the entire device is removably attached to a particular plug from an EKG machine. As with conventional precordial electrodes, the adhesive may not properly stick to patients' precordiums for the reasons described above. In addition, the adhesive electrodes are not reusable and the device does not record signals from the limb leads.
Rubin, U.S. Pat. No. 4,854,323, like Mills et al., describes placing the precordial electrodes in a fixed sequence to avoid electrode reversals. In addition, all six of the electrodes are freely movable along a shapable track to accommodate a variety of body habitus'. However, since there is little or no downward pressure exerted on the chest throughout the normal respiratory cycle, all of the precordial electrodes may not be in simultaneous contact with the chest during recording due to the stiffness of the tube and/or stylet. Further, there are no fixed distances between the locations of any of the precordial leads. This might decrease the intrapersonal reproducibility of the EKG as all precordial electrodes are freely movable. Similar to Arkans, all of the leads exit the device in a cable ending in a plug making for easy attachment to an EKG device. Rubin's invention is intended to be reusable, yet the complex shapes of its parts hinder easy cleaning between patient use. Finally, the disclosed device also does not record signals from the limb leads.
Groeger et al., U.S. Pat. No. 4,957,109, as in the Mills et al. and Arkans teachings, does not disclose significant interpersonal variation in the distances between the lateral precordial recording zones. However, adjustments can be made between patients of various sizes by making kinks in the flexible conductors. The electrodes are attached to the body by an electrically conductive adhesive that is similar to conventional methods using disposable electrodes. The adhesive used may not properly stick to patients' precordiums resulting in poor EKG tracings for the reasons described above. The Groeger et al. device may be used with the wireless telemetry device described in the patent or hard wired to provide automatic or continuous EKG monitoring. In addition, its parts are only partly reusable after each patient.
There is, therefore, a need for an EKG signal recording device that at once provides an accurate, effective, efficient, hygienic, and reusable means of recording EKG's.